81836656865208 has 384 divisors, whose sum is σ = 267112488456000. Its totient is φ = 23145836313600.

The previous prime is 81836656865177. The next prime is 81836656865213. The reversal of 81836656865208 is 80256865663818.

It is a happy number.

81836656865208 is a `hidden beast` number, since 8 + 1 + 8 + 3 + 6 + 6 + 568 + 6 + 52 + 0 + 8 = 666.

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1260913558 + ... + 1260978458.

Almost surely, 2^{81836656865208} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81836656865208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133556244228000).

81836656865208 is an abundant number, since it is smaller than the sum of its proper divisors (185275831590792).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81836656865208 is a wasteful number, since it uses less digits than its factorization.

81836656865208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66132 (or 66115 counting only the distinct ones).

The product of its (nonzero) digits is 796262400, while the sum is 72.

The spelling of 81836656865208 in words is "eighty-one trillion, eight hundred thirty-six billion, six hundred fifty-six million, eight hundred sixty-five thousand, two hundred eight".